An Ethereum platform token built on https://remix.ethereum.org

I am building a token based on ethereum and on RemixEthereum IDE, but i have a problem that i want to generate 100 million tokens and i keep 20% and lock them for 1 year, the code itself locks 20% of tokens That I don't know how to do, please help me and give me more advice, thanks.

Note: I don't need you to create it on the mainnet, I just need the code to run it myself on RemixEthereum,
Prioritize understanding of NFT token working mechanism.